Radiation pattern characterisation of embedded radios emitting modulated signals

Antennas embedded within wireless system are prone to interact with other system components, casing and mounting. These factors cause deviation of the antenna performance from the ideal, and can lead to unexpected performance issues for devices such as wireless sensor nodes. Accurate radiation pattern characterisation requires a reflectionless environment, and a rigorous measurement technique. In this paper, we present the results of a rigorous measurement technique carried out at the UK National Physical Laboratory for the radiation pattern characterisation of embedded radios emitting modulated signals. Using a half-wave dipole antenna a pattern measuring process, which is robust to modulated and bursty signals, is presented and validated against a traditional pattern measuring method. The technique is then applied to a commonly employed wireless sensor network (WSN) platform, the SunSpot, with the influence of various mounting configurations presented.